DN200 User Manual Rel 1.0
Perform these steps:
1.
Mount the external antenna to the same supporting structure as the device, within 3 m (10 ft) distance,
using the bracket supplied in the antenna package.
2.
Connect the antenna to the device’s antenna connector using the RF coaxial cable provided in the
antenna package.
3.
Apply weatherproofing tape to the antenna connectors to help prevent water entering the connectors.
1.14.1 Frequency, Wavelength and Velocity
Instead of saying “cycles per second”, we use the word Hertz (abbreviated Hz) in honor of Heinrich
Hertz who discovered radio waves. Since we are dealing with high frequencies, we use prefixes like kilo
(1,000), Mega (1,000,000) and Giga (1,000,000,000) in front of Hertz, to further simplify the
terminology.
5 cycles per second = 5 Hz
5,000 cycles per second = 5 kHz
5,000,000 cycles per second = 5 MHz
5,000,000,000 cycles per second = 5 GHz
We know that radio waves travel at the speed of light (~186,000 miles per sec. or 3 x 108 meters per
sec.) and we can measure the frequency of the radio waves, therefore we can find out how far the wave
travels in 1 cycle by dividing its’ speed by its’ frequency. We call this a wavelength
Frequency Wavelength
150 MHz 2.0 m
900 MHz 33.3cm
2.4 GHz 12.5cm
5.8 GHz 52cm
1.14.2 The Decibel
The decibel (dB) is a ratio, measured in logarithm, used to measure quantity. A dB has no dimensions.
The decibel is used to compare one power (or voltage level) to another.
Ratio in dB = 10log10 (Power Ratio) = 20log10 (Voltage Ratio)
(Power is proportional to the voltage squared)
20 dB means a power ratio of 102 to 1 or 1,000:1
10 dB means a power ratio of 10 to 1 or 100:1
0 dB means a power ratio of 1 to 1 or 1:1
Because the dB is a ratio, it is dimensionless, however many times reference is made to the unit that is
made as a ratio.
